CODEWITHSUNDEEP
c#regex
erdemgc
erdemgc

Reputation: 1721

Check for the string with decimal place seperated by comma - C#

I need to check this format;

1.234.567,89

Only one comma is permitted for the Entry.

Current code

Regex.Match(((TextChangedEventArgs)e).NewTextValue, @"^[0-9]+(\,[0-9]+)?$");

How can I achieve this?

Upvotes: 1

Views: 442

Answers (2)

ΩmegaMan
ΩmegaMan

Reputation: 31656

Use regex to enforce possibilities by using non capturing lookaheads (?= ?!) which we can enforce all rules before a match.

Rules are

  • Only numbers, a comma or periods, a general rule.
  • Only allow one comma
  • Enforce a comma
  • Don't allow two consecutive periods.

These patterns are commented so use the option IgnorePatternWhitespace or remove comments and join on one line.

Comma Required

^
(?=[\d\.,]+\Z) # Only allow decimals a period or a comma. 
(?=.*,)        # Enforce that there is a comma ahead.
(?!.*\.\.)     # Fail match if two periods are consecutive.
.+             # All rules satisfied, begin matching
$

Comma and following value optional

^
(?=[\d\.,]+\Z) # Only allow decimals a period or a comma. 
(?!.*\.\.)     # Fail match if two periods are consecutive.
[\d.]+         # All rules satisfied, begin matching
(,\d+)?        # If comma found, allow it but then only have decimals       
$              # This ensures there are no more commas and match will fail.

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460168

You should not use regex to check if a string can be parsed to a decimal/double. Use decimal.TryParse (or double.TryParse):

string moneyText = "1.234.567,89";
var myCulture = new CultureInfo("de-DE");
decimal money;
bool validFormat = decimal.TryParse(moneyText, NumberStyles.Currency, myCulture, out money);
if (validFormat)
    Console.WriteLine("Valid format, parsed value was " + money.ToString("C"));

Upvotes: 6

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